Radiator performance scales pretty linearly compared to size, so a double-rad will be able to dump 2/3 of the heat that the triple can, at the same air-water temperature difference. The temperature difference that you'll see depends entirely on what you're trying to cool and how much heat the hardware dumps into the water.

Until just recently, I was cooling both my GTX280 and my i7 920 @ 4.0GHz on a single MCR220, with fans at only ~800rpm, and core temps were in the 40's. While you may be able to get a few more degrees with a larger radiator (or faster fans), a double rad will handle a pair of 280's.

Stacking doesn't work without very high rpm fans - as LP mentioned, the first radiator heats up the air so much that the second radiator can't do anything meaningful, but the two radiators slow down the air so much that performance can actually turn out worse than with a single radiator.

Stacking doesn't work without very high rpm fans - as LP mentioned, the first radiator heats up the air so much that the second radiator can't do anything meaningful, but the two radiators slow down the air so much that performance can actually turn out worse than with a single radiator.

That's pretty much what I've found as well. You'd be better off with two separate ones in series, or even making use of a single 120 rad on the exhaust of the case IMO.

i got you guys... i will drop the radiator stack idea... i just hate radiator's large size... its not easy to cramp it into the case... mid or full tower is much suitable imho... but i am trying to put radiator on normal case... >_>

just curious... which is better... mount the radiator vertically at back of the case... or mount the radiator at top of the case.. are they will doing fine?